Merge branch '353350-display-mutation-errors-cadence-form' into 'master'

Display mutation errors on iteration cadence form

See merge request gitlab-org/gitlab!82641

ee/app/assets/javascripts/iterations/components/iteration_cadence_form.vue

@@ -279,17 +279,11 @@ export default {
           mutation: this.mutation,
           variables: this.variables,
         })
-        .then(({ data, errors: topLevelErrors = [] } = {}) => {
-          if (topLevelErrors.length > 0) {
-            this.errorMessage = topLevelErrors[0].message;
-            return null;
-          }
-
+        .then(({ data } = {}) => {
           const { iterationCadence, errors } = data?.result || {};
 
           if (errors?.length > 0) {
-            [this.errorMessage] = errors;
-            return null;
+            throw new Error(errors);
           }
 
           return getIdFromGraphQLId(iterationCadence.id);

ee/spec/frontend/iterations/components/iteration_cadence_form_spec.js

@@ -172,6 +172,24 @@ describe('Iteration cadence form', () => {
         });
       });
 
+      it('displays mutation errors on failure', async () => {
+        mutationMock = jest.fn().mockResolvedValue(createMutationFailure);
+        createComponent({ mutationMock });
+
+        setTitle(title);
+        setStartDate(startDate);
+        setDuration(durationInWeeks);
+        setRollOver(rollOver);
+        setFutureIterations(iterationsInAdvance);
+
+        clickSave();
+
+        await waitForPromises();
+
+        expect(findError().exists()).toBe(true);
+        expect(findError().text()).toContain('alas, your data is unchanged');
+      });
+
       it('redirects to Iteration page on success', async () => {
         setTitle(title);
         setStartDate(startDate);